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//! Filesystem tree refresh and parsing.
use std::collections::HashMap;
use serde_json::{Value, json};
use crate::base64::base64url_decode;
use crate::crypto::aes::{aes128_cbc_decrypt, aes128_ecb_decrypt};
use crate::error::{MegaError, Result};
use crate::fs::node::{Node, NodeType};
use crate::session::Session;
impl Session {
/// Refresh the filesystem tree from the server.
///
/// This fetches all nodes and decrypts their attributes.
/// Must be called before using `list()`, `stat()`, etc.
///
/// # Example
/// ```no_run
/// # use megalib::Session;
/// # async fn example() -> megalib::error::Result<()> {
/// let mut session = Session::login("user@example.com", "password").await?;
/// session.refresh().await?;
/// let nodes = session.list("/", false)?;
/// # Ok(())
/// # }
/// ```
pub async fn refresh(&mut self) -> Result<()> {
// Fetch filesystem data
let response = self.api_mut().request(json!({"a": "f", "c": 1})).await?;
// Parse share keys from "ok" array
if let Some(ok_array) = response.get("ok").and_then(|v| v.as_array()) {
self.parse_share_keys(ok_array);
}
// Parse nodes from "f" array
let nodes_array = response
.get("f")
.and_then(|v| v.as_array())
.ok_or(MegaError::InvalidResponse)?;
// Preload share keys for our own folders so children can decrypt when no ok entry is usable.
for node_json in nodes_array {
if let Some(1) = node_json.get("t").and_then(|v| v.as_i64()) {
if let (Some(handle), Some(kstr)) = (
node_json.get("h").and_then(|v| v.as_str()),
node_json.get("k").and_then(|v| v.as_str()),
) {
for part in kstr.split('/') {
if let Some((key_handle, encrypted_key)) = part.split_once(':') {
if key_handle == self.user_handle {
if let Ok(enc) = base64url_decode(encrypted_key) {
let dec = aes128_ecb_decrypt(&enc, self.master_key());
if dec.len() >= 16 {
let mut key = [0u8; 16];
key.copy_from_slice(&dec[..16]);
self.share_keys.entry(handle.to_string()).or_insert(key);
// Also populate key_manager for upgraded flows.
if self.key_manager.is_ready() {
self.key_manager.add_share_key_from_str(handle, &key);
}
}
}
}
}
}
}
}
}
let mut nodes = Vec::new();
for node_json in nodes_array {
if let Some(node) = self.parse_node(node_json) {
nodes.push(node);
}
}
// Build node paths
self.build_node_paths(&mut nodes);
// Store nodes
self.nodes = nodes;
// Clear in-use flags for share keys no longer present, persist if changed.
if self.clear_inuse_flags_for_missing_shares() {
let _ = self.persist_keys_with_retry().await;
}
Ok(())
}
/// Parse share keys from the "ok" array response.
///
/// Share keys can be encrypted with:
/// - AES (master key) - for your own shares (key length <= 22 base64 chars)
/// - RSA (private key) - for shares from other users (key length > 22 base64 chars)
fn parse_share_keys(&mut self, ok_array: &[Value]) {
for ok in ok_array {
if let (Some(h), Some(k)) = (
ok.get("h").and_then(|v| v.as_str()),
ok.get("k").and_then(|v| v.as_str()),
) {
// Determine if RSA or AES based on key length (megatools heuristic)
if k.len() > 22 {
// RSA-encrypted share key (from another user)
if let Ok(encrypted) = base64url_decode(k) {
if let Some(decrypted) = self.rsa_key().decrypt(&encrypted) {
if decrypted.len() >= 16 {
let mut key = [0u8; 16];
key.copy_from_slice(&decrypted[..16]);
self.share_keys.entry(h.to_string()).or_insert(key);
}
}
}
} else {
// AES-encrypted share key (your own share)
if let Ok(encrypted) = base64url_decode(k) {
let decrypted = aes128_ecb_decrypt(&encrypted, self.master_key());
if decrypted.len() >= 16 {
let mut key = [0u8; 16];
key.copy_from_slice(&decrypted[..16]);
self.share_keys.entry(h.to_string()).or_insert(key);
}
}
}
}
}
}
/// Parse a single node from JSON.
pub(crate) fn parse_node(&self, json: &Value) -> Option<Node> {
let handle = json.get("h")?.as_str()?.to_string();
let parent_handle = json
.get("p")
.and_then(|v| v.as_str())
.map(|s| s.to_string());
let node_type_int = json.get("t")?.as_i64()?;
let node_type = NodeType::from_i64(node_type_int)?;
let size = json.get("s").and_then(|v| v.as_u64()).unwrap_or(0);
let timestamp = json.get("ts").and_then(|v| v.as_i64()).unwrap_or(0);
let (name, node_key) = match node_type {
NodeType::Root => ("Root".to_string(), Vec::new()),
NodeType::Inbox => ("Inbox".to_string(), Vec::new()),
NodeType::Trash => ("Trash".to_string(), Vec::new()),
_ => {
// Decrypt attributes and node key
let attrs_b64 = json.get("a")?.as_str()?;
let key_str = json.get("k")?.as_str()?;
let node_key = self.decrypt_node_key(key_str)?;
match self.decrypt_node_attrs(attrs_b64, &node_key) {
Some(name) => (name, node_key),
None => return None,
}
}
};
Some(Node {
name,
handle,
parent_handle,
node_type,
size,
timestamp,
key: node_key,
path: None,
link: None,
})
}
/// Decrypt a node key from the "k" field.
fn decrypt_node_key(&self, key_str: &str) -> Option<Vec<u8>> {
// Key format: "handle:encrypted_key" or "handle:encrypted_key/handle2:key2"
for part in key_str.split('/') {
if let Some((key_handle, encrypted_key)) = part.split_once(':') {
// Try master key first (if key_handle matches user_handle)
let decrypt_key = if key_handle == self.user_handle {
Some(self.master_key())
} else {
self.share_keys.get(key_handle).map(|k| k as &[u8; 16])
};
if let Some(key) = decrypt_key {
if let Ok(encrypted) = base64url_decode(encrypted_key) {
let decrypted = aes128_ecb_decrypt(&encrypted, key);
return Some(decrypted);
}
}
}
}
None
}
fn decrypt_node_attrs(&self, attrs_b64: &str, node_key: &[u8]) -> Option<String> {
let encrypted = base64url_decode(attrs_b64).ok()?;
// Use first 16 bytes of node key for attribute decryption
let aes_key: [u8; 16] = if node_key.len() >= 32 {
// File key: XOR first and second 16-byte halves
let mut key = [0u8; 16];
for i in 0..16 {
key[i] = node_key[i] ^ node_key[i + 16];
}
key
} else if node_key.len() >= 16 {
node_key[..16].try_into().ok()?
} else {
return None;
};
let decrypted = aes128_cbc_decrypt(&encrypted, &aes_key);
// Attributes are JSON prefixed with "MEGA"
let text = String::from_utf8_lossy(&decrypted);
if !text.starts_with("MEGA") {
return None;
}
// Parse JSON after "MEGA" prefix
let json_str = text.trim_start_matches("MEGA").trim_end_matches('\0');
let attrs: Value = serde_json::from_str(json_str).ok()?;
attrs
.get("n")
.and_then(|v| v.as_str())
.map(|s| s.to_string())
}
/// Build full paths for all nodes.
fn build_node_paths(&self, nodes: &mut [Node]) {
// Create handle -> node index map
let handle_map: HashMap<&str, usize> = nodes
.iter()
.enumerate()
.map(|(i, n)| (n.handle.as_str(), i))
.collect();
// First, compute all paths
let paths: Vec<String> = (0..nodes.len())
.map(|i| self.build_node_path(nodes, i, &handle_map, 0))
.collect();
// Then assign them
for (i, path) in paths.into_iter().enumerate() {
nodes[i].path = Some(path);
}
}
/// Recursively build a node's path.
fn build_node_path(
&self,
nodes: &[Node],
idx: usize,
handle_map: &HashMap<&str, usize>,
depth: usize,
) -> String {
// Prevent infinite loops
if depth > 100 {
return format!("/{}", nodes[idx].name);
}
let node = &nodes[idx];
// Root nodes have path "/"
if matches!(
node.node_type,
NodeType::Root | NodeType::Inbox | NodeType::Trash | NodeType::Network
) {
return format!("/{}", node.name);
}
// Find parent and prepend its path
if let Some(parent_handle) = &node.parent_handle {
if let Some(&parent_idx) = handle_map.get(parent_handle.as_str()) {
let parent_path = self.build_node_path(nodes, parent_idx, handle_map, depth + 1);
return format!("{}/{}", parent_path.trim_end_matches('/'), node.name);
}
}
format!("/{}", node.name)
}
}